The present invention relates to a method and apparatus for reducing or eliminating propagating buckle failures in underwater pipelines. Deep water offshore pipelines having high diameter to wall thickness ratios can buckle in one section and the buckle can propagate along the pipeline until it either encounters an obstacle such as a valve body or until the water depth is substantially decreased.
Buckle failures in underwater pipelines are also induced by pipelaying operations during construction. Pipelaying apparatus maintains the pipe in tension by gripping means engaging the outside diameter of the pipe and as a result tends to oval pipe having thin walls. By ovaling the pipe, the buckle resistance can be reduced by as much as 40 percent if the pipe is deformed one wall thickness. Such a reduction of the buckle resistance is substantial. A result of this is that heavier walled pipe is used, greatly increasing the cost of the underwater pipeline. Buckling may also be induced after construction and during operation of the pipeline by damage caused by external forces such as dragging ship anchors, mud slides, water-induced movement or other disturbances. Reference may be had to U.S. Pat. Nos. 3,768,269 and 3,747,356.